The invention relates to a device for detecting objects lying in the earth, especially explosive objects, such as non-exploded mines, grenades, munitions or bombs, with a mobile device on which a jib swivellable at least about a vertical axis is mounted, on the free end of which several measuring heads are arranged.
Former military sites often have explosive objects in the earth which must be removed from the earth before the terrain can be directed toward a new use. Since it is usually a question of very large areas, it would be too expensive to remove all the earth in the upper soil layers and search for the objects mentioned.
In order to be able to implement cleanups of old military encumbrances with a reasonable expenditure, it is first of all necessary to detect not yet exploded objects and to remove only the earth at the find sites and cleanse it of explosive objects in a second step. Since large surface segments of land must be combed, conventional detection devices are not practicable for this and are associated with great dangers for life and limb of the personnel.
With known manual searching apparatus which are guided by operators over the ground, only relatively narrowly restricted areas can be searched with a reasonable expenditure of time. Moreover, the danger for operating personnel is very great, because the person must walk over the grounds to be searched with the metal detector and can cause the objects detected to detonate through inattention under certain circumstances.
Moreover, vehicles are known on the front side of which metal detectors are firmly installed, so that only the area in front of the vehicle can be searched for explosive objects. Even with these vehicles, the surface yield is not sufficient. A further disadvantage consists in that, as a rule, only flat ground can be examined because the measuring heads are rigidly fastened on the vehicle. Uneven terrain therefore leads to considerable errors in identifying the location of the objects, which has as a consequence that the cleanup troops are either exposed to a heightened risk or must carry off more ground than is necessary in order to discover the objects, or that on account of the cants in troughs dead areas arise, so that many explosive objects are not located at all.
U.S. Pat. No. 4,021,725 describes a mine detecting apparatus which has a jib on the front side of a mobile device on whose free end a detection device is arranged. The jib is swivellable around a vertical and/or horizontal axis. The detection device possesses several probes in order be able to construct the position of magnetic dipoles and a map with the position of these discovered objects. During the forward movement, the jib executes an oscillating swinging movement. Owing to the fact that the probes are arranged in a row transverse to the direction of travel, the terrain is only probed along a line. Further, the mine detecting apparatus is usable only for level terrains. As soon as uneven terrains emerge, recognition of the position is erroneous, or mines located in the soil are not identified at all.
DE 42 27 461 A1 describes a mine reconnaissance and detector system which has a remote-controlled vehicle which is connected with a processing and control unit through an interconnecting cable. The sensor device is installed firmly on the mobile device, so that with uneven terrain erroneous measurements likewise occur. The marking device is located at the back end of this vehicle with the disadvantage that the exact position of discovered objects cannot be marked.
DE 35 26 492 A1 describes an apparatus for discovering metal, particularly mines. The metal seeking probe has a spool, whose diameter is greater than half the width of the vehicle, on which the probe is fastened by means of a carrier device. The carrier device is displaceable only in a vertical direction.
FR51551 describes a mobile mine searching device with a jib which is swivellable in a vertical direction about a horizontal axis, on which jib is suspended a net-shaped arrangement with measuring heads.